1. Field of the Invention
The present invention relates to a head suspension assembly of a disk drive for supporting and moving a head for writing and reading information on and from a recording medium.
2. Description of the Related Art
In general, a disk drive such as a hard disk drive (HDD) includes a head suspension assembly for supporting a head which writes or reads information on and from a track of a disk rotatably installed in a housing.
The head suspension assembly includes a suspension, that is, a rod beam, supported at an end portion of an actuator arm rotated by a voice coil motor (VCM), a Gimbal connected to an end portion of the suspension, and a slider supported at the Gimbal and having the head. The suspension rotated with the actuator arm moves the slider to a desired position across the disk. The head moved while being supported at the slider must be positioned to correspond to a predetermined track of a plurality of tracks provided at the disk where information is to be written or read. The accuracy of the head""s tracking is important for the integrity of information being written and read.
It is a recent trend for the size of a disk drive itself to be small while the storage capacity thereof is large. Accordingly, the tracks per inch (TPI) of a disk increases. As the TPI and the rate of rotation of a disk increase, accurate control of the position of the head becomes difficult.
To solve the above problem, a head suspension assembly having an additional accurate tracking motor or micro actuator is suggested and an example thereof is shown in FIG. 1.
FIG. 1 shows a head suspension assembly disclosed in U.S. Pat. No. 5,857,347. The head suspension assembly includes a rod beam 10 having a horizontal portion 15 formed across an end portion 11 and a middle end portion 13 thereof and supported at an end portion of an actuator arm (not shown). A Gimbal 17 is provided at the end portion 11 of the rod beam 10. A slider (not shown) having a head for reading/writing (not shown) is supported at the Gimbal 17. Also, the end portion 11 and the middle end portion 13 of the rod beam 10 are elastically connected by a connection portion 30. A micro actuator 20 having a first coil unit 21 and a second coil unit 23 is installed around the connection portion 30.
When current is applied to coils 22 and 24 of the first and second coil units 21 and 23, a vertical repulsive force is generated due to an electromagnetic force between the coil units 21 and 23. Then, each of the coil units 21 and 23 is moved up and down by the vertical repulsive force and vertical rail portions 31 and 33 of the connection portion 30 is bent in a horizontal direction. Thus, the end portion 11 pivots in a horizontal direction, that is, in a track direction, with respect to the middle end portion 13 so that the slider is minutely adjusted.
However, such a conventional head suspension assembly requires a large number of parts and the structure of the rod beam is complicated so that a practical application is difficult and production cost is high. Also, a large driving force is needed to drive the rod beam including the slider. However, much power is lost in the process of converting the vertical repulsive force generated between the coil units to a horizontal direction through the connection portion.
To solve the above problems, it is an objective of the present invention to provide a head suspension assembly of a disk drive having an improved structure in which the slider can pivot with respect to the rod beam.
Accordingly, to achieve the above objective, there is provided a head suspension assembly of a hard disk drive comprising a rod beam coupled to an end portion of an actuator arm capable of pivoting in a direction following tracks of a disk, a slider supported at an end portion of the rod beam for reading and writing data from and on the disk, a micro actuator including first and second magnetic members installed at the rod beam and the slider, respectively, and being moved by an electromagnetic force between the magnetic members to allow the slider to minutely move with respect to the rod beam, and a connection device for elastically connecting the first magnetic member and the second magnetic member.
It is preferred in the present invention that the first magnetic member comprises a first coil base supported at the end portion of the rod beam and a pair of first coils installed at a bottom surface of the first coil base and forming a magnetic field during driving, and the second magnetic member comprises a second coil base installed on an upper surface of the slider to correspond to the first coil base and a second coil installed on an upper surface of the second coil base to correspond to the first coil.
Also, it is preferred in the present invention that the first coils are installed in a circular shape at the left and right sides with respect to a predetermined center line on the slider crossing the track direction and, when current is applied, an induced magnetic field is formed in a vertical direction at a surface of the slider.
Also, it is preferred in the present invention that the second coil is wound in a rectangular shape at an upper surface of the second coil base to generate an electromagnetic force at left and right effective coil portions with respect to a predetermined center line on the slider crossing the track direction.
Also, it is preferred in the present invention that a recessed portion for accommodating the first coil to be separated a predetermined distance from the second coil is formed at the lower surface of the first coil base.
Also, it is preferred in the present invention that the connection device comprises a connection plate having an aperture formed at a bottom surface of the first magnetic member for accommodating the second magnetic member to move therein and an elastic member for elastically connecting an inner surface of the aperture and an outer surface of the second magnetic member.
Also, it is preferred in the present invention that the elastic member comprises hairpin springs symmetrically provided with respect to a predetermined center line on the slider crossing the track direction.
Also, it is preferred in the present invention that the elastic member comprises a torsion bar connected between the inner surface of the aperture and either a front end portion or a rear end portion of the second magnetic member to allow the second magnetic member to pivot with respect to the first magnetic member while being bent by an electromagnetic force between the magnetic members.
Also, it is preferred in the present invention that the connection plate and the elastic member are integrally formed with the second magnetic member.
Also, it is preferred in the present invention that the first magnetic member comprises a magnet base supported at the end portion of the rod beam and having a recessed portion formed at a bottom surface thereof and a pair of magnets installed at the recessed portion of the magnet base such that directions of magnetization are opposite to each other.